This invention relates to olefin hydration, especially for production of di-isopropyl ether (DIPE) from C.sub.3 + olefinic feedstock. Particularly, the invention relates to a novel technique for recovering dry DIPE product from reactor effluent.
The need to eliminate lead-based octane enhancers in gasoline has provided incentive for development of processes to produce high octane gasolines blended with lower aliphatic alkyl ethers as octane boosters. Supplementary fuels are being vigorously developed in the petroleum refining industry. Lower molecular weight alcohols and ethers such as isopropyl alcohol (IPA), and diisopropyl ether (DIPE) are in the boiling range of gasoline fuels and are known to have a high blending octane number. They are useful octane enhancers. In addition, by-product propene (propylene) from which IPA and DIPE can be made is usually available in a fuels refinery, typically as a C.sub.3 +aliphatic stream rich in propene and propane. Feedstocks of particular interest are light hydrocarbon streams rich in propene, which are often accompanied by significant amounts of propane, ethene, ethane and other light gases.
Catalytic hydration of olefins to provide alcohols and ethers is established technology for production of the IPA and DIPE and is of significant commercial importance. Olefin hydration employing large pore zeolite (i.e. 7+Angstroms) or medium pore (5-7 .ANG.) catalyst is a known synthesis method. Recently, processes for the direct hydration of olefins to provide alcohols and ethers using porous shape selective metallosilicate zeolite catalyst, such as zeolite Beta have been disclosed in U.S. Pat. No. 4,857,664 (Huang et al.), U.S. Pat. No. 4,886,918 (Sorensen et al), U.S. Pat. Nos. 5,138,102 and 5,162,591 (Beech et al), incorporated herein by reference. Prior processes have attempted to provide a dry DIPE product by various recovery techniques.
It is a main object of this invention to provide an improved process for olefin hydration in a more economical manner and with improved yields of dry ether product. It is a further object to provide novel product recovery techniques for use in DIPE reactor systems.